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Syphilis

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Background

Syphilis, a genital ulcerative disease, causes significant complications if untreated and facilitates the transmission of HIV infection. Untreated early syphilis in pregnant women results in perinatal death in up to 40% of cases and, if acquired during the 4 years before pregnancy, can lead to infection of the fetus in 80% of cases.1

The rate of P&S syphilis reported in the United States decreased during the 1990s; in 2000, the rate was the lowest since reporting began in 1941 (Figure 33). The low rate of infectious syphilis and the concentration of the majority of syphilis cases in a small number of geographic areas in the United States led to the development of CDC’s National Plan to Eliminate Syphilis, which was announced by Surgeon General David Satcher, MD, PhD, in October 1999 and revised in May 2006.2

Although the rate of P&S syphilis in the United States declined 89.7% during 1990–2000, the rate increased annually during 2001–2009. Overall increases in rates were observed primarily among men (increasing from 3.0 cases per 100,000 population in 2001 to 7.8 cases in 2009). After persistent declines during 1992–2003, the rate among women increased from 0.8 cases in 2004 to 1.4 cases in 2009.

Syphilis remains a major health problem in the South and in urban areas in other regions of the country. Increases in cases among MSM (including men having sex with both men and women) have occurred and have been characterized by high rates of HIV co-infection and high-risk sexual behaviors.3–7 The estimated proportion of P&S syphilis cases attributable to MSM increased from 7% in 2000 to 64% in 2004.8,9 In 2005, CDC requested that all state health departments report the sex of sex partners for persons with syphilis. In 2009, 62% of P&S syphilis cases in 44 states and the District of Columbia that provided information about sex of sex partners were among MSM. Of reported male cases with P&S syphilis, sex of sex partner information in 2009 was available for 80%.

Syphilis—All Stages (P&S, Early Latent, Late, Late Latent, and Congenital)

During 2008–2009, the number of cases of early latent syphilis reported to CDC increased 5.4% (from 12,401 to 13,066 cases), while the number of cases of late and late latent syphilis decreased 13.1% (from 19,945 to 17,338 cases) (Tables 1, 35, and 37). The total number of cases of syphilis (P&S, early latent, late, late latent, and congenital) reported to CDC decreased 3.2% (from 46,291 to 44,828 cases) during 2008–2009 (Table 1).

P&S Syphilis—United States

P&S syphilis cases reported to CDC increased from 13,500 in 2008 to 13,997 in 2009, an increase of 3.7%. The rate of P&S syphilis in the United States in 2009 (4.6 cases per 100,000 population) was 4.5% higher than the rate in 2008 (4.4 cases) (Figure 33, Table 1).

P&S Syphilis by Region

The South accounted for 53.0% of the P&S syphilis cases in 2009 and 49.7% in 2008. During 2008–2009, rates increased 10.0% in the South (from 6.0 to 6.6 cases per 100,000 population), 2.7% in the Northeast (from 3.7 to 3.8 cases), and 7.7% in the Midwest (from 2.6 to 2.8 cases). Rates decreased in the West by 11.6% (from 4.3 to 3.8 cases) (Figure 35, Table 25).

P&S Syphilis by State

In 2009, the 13 states with the highest rates of P&S syphilis accounted for 75% of all U.S. cases of P&S syphilis. The rate of P&S syphilis in these 13 states exceeded the national rate of 4.6 cases per 100,000 population. Of these states, 10 were in the South (Figure 36, Table 24).

P&S Syphilis by Metropolitan Statistical Area

The rate of P&S syphilis in 2009 for the 50 most populous MSAs (6.2 cases per 100,000 population) exceeded the overall rate for the United States (4.6 cases) (Table 28). The rate increased in 25 of these 50 MSAs (50%) during 2008–2009.

P&S Syphilis by County

In 2009, a total of 2,194 of the 3,141 counties (69.9%) in the United States reported no cases of P&S syphilis, compared with 2,180 counties (69.3%) in 2008 (Figure 37). In 2009, half of the total number of P&S syphilis cases was reported from 29 counties and two cities (Table 31).

P&S Syphilis by Sex

The rate of P&S syphilis increased 4.0% among men (from 7.5 to 7.8 cases per 100,000 men) during 2008–2009 (Figure 34, Table 27). During this same period, the rate decreased 6.7% among women (from 1.5 to 1.4 cases per 100,000 women) (Figure 34, Table 26).

P&S Syphilis by Age

In 2009, the rate of P&S syphilis was highest among persons aged 20–24 years and 25–29 years (13.4 and 11.3 cases per 100,000 population, respectively) (Figure 38, Table 33).

During 2008–2009, rates for men increased the most in those aged 15–19 years and 20–24 years (Figures 38–40, Table 33). Rates for men are now highest in those aged 20–24 years, and the rates decrease with age. These data indicate a considerable shift since 2000, when the highest rates were in men aged 25–34 years. In women, rates increased the most among those aged 15–19 years and 30–34 years (Figures 38–40, Table 33), but have remained highest in those aged 20–24 years.

P&S Syphilis by Sex and Sex Behavior

The male-to-female ratio for P&S syphilis rates has risen steadily since 1996, when it was 1.2, reflecting higher rates in men than women (Figure 34). This increase is consistent with an increase in P&S syphilis rates among MSM. In 2008, this ratio decreased to 5.0, but in 2009, it increased to 5.6.

In 2005, CDC began collecting information on the sex partners of patients with P&S syphilis. In 2009, this information was available for 80% of male cases.

In 2009, among men who have sex with women only (MSW) with P&S syphilis, 39.4% had primary syphilis, and 60.6% had secondary syphilis. Among women with P&S syphilis, 15.9% had primary syphilis, and 84.1% had secondary syphilis. Among MSM, 23.9% had primary syphilis, and 76.1% had secondary syphilis (Figure 42).

Among women with P&S syphilis, 19.0% were white, 72.9% were black, 6.5% were Hispanic, and 1.5% were of other races/ethnicities. Among MSW, 16.1% were white, 68.4% were black, 13.4% were Hispanic, and 2.1% were of other races/ethnicities. Among MSM, 37.7% were white, 39.6% were black, 19.1% were Hispanic, and 3.6% were of other races/ethnicities (Figure 43).

P&S Syphilis by Race/Ethnicity, Age, and Sex

In 2009, the rate of P&S syphilis among non-Hispanic blacks was highest among women aged 20–24 years (29.6 cases, an 18.9% increase from 24.9 cases in 2008) and among men aged 20–24 years (94.2 cases, a 27.0% increase from 74.2 cases in 2008) and 25–29 years (79.2 cases). For non-Hispanic whites, the rate was highest among women aged 20–24 years (1.3 cases) and among men 40–44 years (9.9 cases).

For Hispanics, the rate was highest among women aged 20–24 years (2.0 cases) and among men aged 20–24 years (18.9 cases). For Asians/Pacific Islanders, the rate was highest among women aged 35–39 years (0.6 cases) and among men aged 30–34 years (6.8 cases). For American Indians/Alaska Natives, the rate was highest among women aged 25–29 years (3.1 cases) and among men aged 35–39 years (11.4 cases) (Table 34B).

P&S Syphilis by Reporting Source

In 1990, 25.6% of P&S syphilis cases were reported from sources other than STD clinics; this figure increased to 39.2% in 1998. During 1998–2009, the proportion of cases reported from sources other than STD clinics increased from 39.2% to 64.9% (Figure 44, Table A2). During 2001–2009, the number of cases among males reported from non-STD clinic sources increased sharply, while the number reported from STD clinics increased only slightly (Figure 44).

During 2009, patients with P&S syphilis usually sought care from private physicians or STD clinics. More cases of syphilis among MSM were reported from private physicians (34.8%) than STD clinics (33.0%) (Figure 45). More cases among women and MSW were reported from STD clinics than from private physicians.

Congenital Syphilis—United States

Overall, the rate of congenital syphilis decreased during 2008–2009 (from 10.4 to 10.0 cases per 100,000 live births); a 17% rate increase occured during 2006–2007 (Table 40). In 2009, a total of 427.0 cases were reported, an increase from 339.0 in 2005. The increase in the rate of congenital syphilis since 2005 (when the rate reached a low point of 8.2 cases per 100,000 live births) might be associated with the increase in the rate of P&S syphilis among women that has occurred since 2004 (Figure 46).10

In 2009, a total of 33 states and 1 outlying area had 1 or more cases of congenital syphilis (Tables 39 and 40).

Syphilis Among Special Populations

More information about syphilis and congenital syphilis in racial and ethnic minority populations, adolescents, MSM, and other populations at higher risk can be found in the Special Focus Profiles.

Syphilis Summary

In recent years, MSM have accounted for an increasing number of syphilis cases in the United States.9 According to information reported in 44 states and the District of Columbia, 62% of P&S syphilis cases are among MSM. Although the majority of U.S. syphilis cases have occurred among MSM, syphilis among MSW is an emerging problem.11